The long term goal of our research is to define the functional roles of src and myc gene products in Drosophila development. To this end, we have documented the expression of these genes during oogenesis and early embryonic development. These studies, which are detailed in the progress report have shown that the three major src-related and the myc-related Drosophila sequences are maternally inherited and are functional as mRNA during early development. We will extend our studies during the next year through the application of two types of in situ analysis and conventional biochemical techniques. src expression during embryogenesis and oogenesis: (1)\by in situ hybridizations to histological sections, determine the localizations of src transcripts; (2)\analyze the patterns of synthesis of src proteins by immunoprecipitation of [[unreadable]35[unreadable]S]methionine-labeled proteins; (3)\determine the presence of src protein in various stages of development by antibody staining of nitrocellulose replicas of electrophoretically separated proteins; and (4)\determine the intracellular location of src proteins by immunostaining of histological sections of different developmental stages. Genetic approaches to Drosophila src function: (1)\use a viral src gene linked to a heat shock promoter as dominant mutation whose expression can be controlled. Biochemical approaches to Drosophila src function: (1)\immuno-affinity purification of Drosophila src proteins followed by in vitro kinase assays to determine the functional conservation of the Drosophila proteins. (X)